A method has been adopted where, in a plurality of local file storage apparatuses which are connected to a remote file storage apparatus via a network, copies of file write data are transferred at regular intervals to a remote file storage apparatus as replication files and the replication files are stored in the remote file storage apparatus as backup files. Here, technology which deletes data of files in the local file storage apparatus (edge-side file storage apparatus), manages the files as stub files, and suppresses an increase in the capacity of storage devices for storing files (see PTL 1).